Oil-soluble aminated oxidized olefin copolymers

ABSTRACT

Lubricant additives exhibiting dispersant and viscosity-index (V.I.) improving properties are obtained by the amination of oxidized high molecular weight amorphous copolymers of essentially ethylene and propylene having a number average molecular weight of from about 1,500 to about 200,000 or more, and at least about 150 pendant methyl groups per 1,000 chain carbon atoms, with a primary or secondary aliphatic amine or polyamine, said reactants being employed in the molar ratio of from about 1:2 to about 1:20, respectively; the aminated oxidized copolymers having a number average molecular weight in the range of from about 1,500 to about 20,000 exhibit excellent dispersancy properties, while those having a number average molecular weight of at least about 20,000 exhibit bi-functional dispersancy and V.I. improving properties.

Culbertson et al.

Feb. 4, 1975 OIL-SOLUBLE AMINATED OXIDIZED OLEFIN COPOLYMERS Inventors: George S. Culbertson, Downers Grove; Robert E. Karll, Batavia, both of I11.

Assignee: Standard Oil Company, Chicago, 111.

Filed: Aug. 8, 1972 Appl. No.: 278,720

U.S. Cl..... 252/515 R, 252/515 A, 260/882 S Int. Cl C10m l/32 Field of Search 252/515 A, 51.5 R;

References Cited UNITED STATES PATENTS Primary Examiner-Daniel E. Wyman Assistant Examiner-A. P. Demers Attorney, Agent, or FirmFred R. Ahlers; Arthur G. Gilkes; William T. McClain [57] ABSTRACT Lubricant additives exhibiting dispersant and viscosity-index (V.l.) improving properties are obtained by the amination, of oxidized high molecular weight amorphous copolymers of essentially ethylene and propylene having a number average molecular weight of from about 1,500 to about 200,000 or more, and at least about 150 pendant methyl groups per 1,000 chain carbon atoms, with a primary or secondary aliphatic amine or polyamine, said reactants being employed in the molar ratio of from about 1:2 to about 1:20, respectively; the aminated oxidized copolymers having a number average molecular weight in the range of from about 1,500 to about 20,000 exhibit excellent dispersancy properties, .while those having a number average molecular weight of at least about 20,000 exhibit bi-functional dispersancy and V.I. improving properties.

12 Claims, No Drawings OIL-SOLUBLE AMINATED OXIDIZED OLEFIN COPOLYMERS BACKGROUND OF THE INVENTION Lubricant deterioration in high speed engines causes the formation of lacquer, sludge and carbon deposits on the interior surfaces of the engines which accelerates wear and reduces engine efficiency. To reduce the tendency for such deleterious products to deposit on the surfaces of the engine it is known to incorporate in the lubricating oil additives having dispersancy and/or detergency properties.

The continuing search for and the necessity of having available ashless dispersants and/or detergents additives for motor oils is well known. Since the development of the positive crankcase ventilation system (PCV) there is a greater demand than ever for improved additives of such types.

It is also well known that lubricating oils have a tendency to become thin at elevated temperatures while becoming thick at low temperatures, and thus it is generally necessary to add additives to such lubricants which improve their viscosity-temperature relationships. For example, in the case of a crankcase lubricating oil in a cold engine, it is desirable that the oil not become so thick that it is difficult to start the engine; while, when the engine is hot it is necessary that the oil remain sufficiently viscous that an oil film is maintained between the moving parts.

Various products have been developed for the purpose of providing the dispersant and/or detergent function. Neutral and overbased metallo-organic compounds, such as the alkaline earth salts of sulfonic acids, and hydrocarbon P 5 reaction products were among the first additive agents used for this purpose.

LII

Their in-service drawbacks include the formation of undesirable metal-ash thermal decomposition products. Other proposed additives were amine salts, amides, imides and amidines of polybutenyl-substituted polycarboxylic acids. Still other proposed additives were combinations of alkaline earth sulfonates and Mannich condensation products of low molecular weight alkyl substituted hydroxyaromatic compounds, amines having at least one replaceable hydrogen on a nitrogen, and aldehydes: alkaline earth salts of such Mannich condensation products have also been suggested.

SUMMARY OF THE INVENTION In accordance with the present invention, the herein described lubricant additives are prepared by reacting simultaneously, at a temperature of about 140-350F., an oxidized copolymer (as hereinafter defined) of essentially ethylene and propylene with an aliphatic amine or polyamine, and recovering the resultant reaction product; said reactants being employed in the molar ratio of from about 1:2 to about 1:20.

In the preparation of the additive of this invention it is desirable to conduct the reaction in the presence of a non-reactive organic solvent or diluent, such as, for example, an aromatic hydrocarbon solvent, e.g., benzene, xylene, toluene, etc., or an aliphatic hydrocarbon solvent, such as, for example, hexane. Particularly suitable as a solvent or diluent is a low viscosity hydrocarbon oil, such as a solvent-extracted SAE 5W mineral oil. The use of a solvent or diluent is advantageous to facilitate the mixing of the reactants, and in the control of the reaction temperatures.

THE COPOLYMER The term copolymer as used herein and in the appended claims, refers to amorphous copolymers derived from essentially ethylene and propylene; however, such copolymers may contain minor amounts, i.e., up to 10 percent, based on the molar amounts of the monomeric ethylene and propylene units in the copolymer, of polymerized units derived from other'olefin monomers. Such other olefine monomers include olefins of the general formula RCH CH in which R is an aliphatic or cycloaliphatic radical of from 2 to about 20 carbon atoms, for example, butene-l, hexene-l,4-methyl-1-pentene, decene-l, vinylidene norbornene, 5-methylene-2-norbornene, etc. Other olefine monomers having a plurality of double bonds may be used, in particular diolefins containing from about 4 to about 25 carbon atoms, e.g., 1,4-butadiene, 1,3-hexadiene, 1,4-pentadiene, 2-methyl-1,5- hexadiene, 1,7-octadiene etc.

Suitable ethylene-propylene copolymers contain from about 30 to about 65, preferably from about 35 to about 45 mole percent propylene, have a number average molecular weight of at least about 21,500, i.e., from about 21,500 to about 200,000 or more, and preferably for bi-functional additives from about 25,000 to about 40,000, and contain at least pendant methyl groups per 1,000 chain carbon atoms.

A particularly suitable ethylene-propylene copolymer is one having the following characteristics:

Number Average Molecular Weight 25,000-35,000

Percent (Molar) propylene monomer 38-42 Pendant Methyl Groups per 1,000

Chain Carbon Atoms Inherent Viscosity l.72.0 (A) Gardner Viscosity U-V (B) Mooney Viscosity 20-35 (C) (A) 0.1 gram copolymer in 100 cc decalin at 135C. (B) 8.0% copolymer in toluene at 25C. (C) ASTM D4646 Methods of preparation of the copolymers are well known; such methods are described in many United States Patents, such as, among others, U.S. Pat. Nos. 2,700,633; 2,726,231; 2,792,288; 2,933,480; 3,000,866; 3,063,973; 3,093,621 and others.

OXIDATION OF THE COPOLYMER The oxidation can be accomplished by contacting the copolymer under suitable conditions of temperature and at atmospheric or elevated pressures, with an oxidizing agent such as air or free oxygen, or any oxygencontaining material capable of releasing oxygen under the oxidation conditions. If desired, the oxidation can be conducted in the presence of known oxidation catalysts such as platinum or a platinum group metal, and compounds containing metals such as copper, iron, cobalt, cadmium, manganese vanadium etc. The oxidation can be carried out by methods described in U.S. Pat. Nos. 2,982,728; 3,316,177; 3,153,025; and 3,365,499, and 3,544,520.

Generally, the oxidation can be carried out over a wide temperature range, depending upon the oxidizing agent used; for example, with an active oxidizing agent, e.g., S0 temperatures in the range of 40F. to 400F. have been used, while with less active oxidizing agents,

e.g., air, temperatures in the range of 100-800F. have been used. Further, depending upon the rate desired, the oxidation can be conducted at sub-atmospheric, atmospheric or super-atmospheric pressures, and in the presence or absence of oxidation catalysts. The conditions of temperature, pressure, oxygen content of the oxidizing agent, the rate of introducing the oxidizing agent, the catalyst employed, if any, etc., are correlated and controlled by those skilled in the art, so as to obtain the desired optimum results.

The following will illustrate one method of oxidizing the copolymer; to a copolymer of ethylene and propylene (1 part), having a number average molecular weight of about 28,000, was added a solvent-extracted SAE W mineral oil (9 parts) in an open reaction vessel, and the mixture slowly stirred and heated at a temperature of 360F., under an inert gas atmosphere, until solution of the rubber-like polymer in the solvent was effected. Maintaining the 360F. temperature, the mixture was rapidly agitated in an atmosphere composed of 50 percent air and 50 percent nitrogen, to promote the oxidation of the copolymer. A 50:50 air-nitrogen ratio was used to preclude the possibility of an explosive mixture being formed. Reaction in the described manner was continued for 2.5-4.0 hours. About 2.5-4.5 oxygen atoms per molecule of the copolymer were introduced under such oxidation conditions.

THE AMINE REACTANT The amine reactant used in the preparation of the products of the present invention are primary or secondary aliphatic amines and diamines of the general formula H N(CH ),,NH wherein y is an integer 3 to 10, said amines and diamines containing up to about carbon atoms in the alkyl group, the polyalkylene polyamines of the general formula wherein A is a divalent alkylene radical of about 2 to about 6 carbon atoms, and x is an integer from 1 to about 10. illustrative of suitable amines are: methylamine, dibutylamine, cyclohexylamine, propylamine decylamine, ethylene diamine, trimethylene diamine, tetramethylene diamine, hexamethylene diamine, diethylene triamine, triethylene tetramine, tetraethylene pentamine, tripropylene tetramine, tetrapropylene pentamine, and other polyalkylene polyamines in which the alkylene groups contain suitably up to about 10 carbon atoms.

Aminated above described oxidized copolymers having number average molecular weights in the range of from about 1,500 to about 20,000 are used primarily as dispersant additives, while the aminated oxidized copolymers having number average molecular weights in the range of from about 20,000 to about 200,000, or more, and preferably in the range of from about 25,000 to about 40,000, are suitable bi-functional additives which impart dispersancy and V.I. improving properties to lubricants.

The chemical composition of the reaction product of this invention cannot be characterized with preciseness by chemical structural formula. While it is believed that the oxidation of the copolymer produces predominately ketones, it is known that minor amounts of aldehydes, acids and perhaps esters may also be present. in

view of the complex nature of the oxidized reaction product, the precise composition of such product cannot be defined by its chemical structure, but rather must be defined by its method of preparation.

The herein described reaction products of the present invention are effective dispersant and V.1. improving additives in oleaginous lubricant compositions when used in amounts of from about 0.1 to about 10 percent. Suitable lubricating base oils are mineral oils, i.e., petroleum oils, synthetic lubricating oils, such as those obtained by the polymerization of hydrocarbons, and other well-known synthetic lubricating oils, and lubricating oils of animal or vegetable origin. Concentrates of a suitable oil base containing more than 10 percent, i.e., from about 10 to about percent or more, of the additive of the present invention, alone or in combination with other well-known additives, can be used for blending with lubricating oils in proportions desired for particular conditions or use to give a finished product containing from about 0.1 to about 10 percent of bi-functional additive of this invention.

PREFERRED EMBODIMENTS OF THE INVENTION The following examples are illustrative of preferred embodiments of the present invention.

EXAMPLE 1 PART A. OXIDATION OF THE COPOLYMER 500 grams of an ethylene-propylene copolymer, having a number average molecular weight of l,800-2,000, were placed in an open reaction vessel and heated at 310F. for 3 hours while being vigorously stirred. At the end of three hours the oxidation was complete. Infrared spectrum of the product showed strong absorption at 5.8 microns, indicating carbonyl, and silica gel chromatography showed percent conversion to carbonyl. The oxygen content of the product was 3.7 percent.

PART B. AMINATION OF THE OXlDlZED CO- POLYMER Here 0.285 mole of the oxidized copolymer, from Part A, above, was heated at 300F., under 1.0 CFH nitrogen, while 49 grams (0.258 mole) tetraethylene pentamine (TEPA) was added over a 10 minute period. Heating and moderately rapid stirring was continued for 1 hour, during which time the water formed as a byproduct was swept from the reaction zone with nitrogen bleed. The recovered product was essentially hazefree and contained 1.25 percent nitrogen (theoretical 1.25 percent).

If desired, the amination step can be carried out in the presence of a solvent, such as benzene, toluene or xylene, by adding the TEPA to a refluxing solution of the oxidized copolymer in an equal weight of the solvent. Water of reaction, formed, is co-distilled out over an one hour period, using a suitable water-trap. The solvent is then removed by distillation, using nitrogen as a stripping agent.

EXAMPLE 11 PART A. PREPARATION OF THE COPOLYMER An amorphous ethylene-propylene copolymer was prepared by solution polymerization using a Ziegler- Natta type catalyst, vanadium oxychloride solution in combination with ethylaluminum sesquichloride solution. Dry heptane (1,200 ml.) was saturated at 86F. and 30 p.s.i.g. with a gas mixture consisting of 50 mole percent ethylene, 35 mole percent propylene and mole percent hydrogen. The gas mixture was introduced at the rate of 100 liters per hour, circulated through the heptane, and then passed out of the system. When the saturation was complete, the addition of the catalyst components, in heptane solution, was started. The vanadium oxytrichloride solution (0.370 percent by weight) was introduced into the olefin mixture at the rate of 13 ml/hr., and the ethylaluminum sesquichloride solution (0.459 percent wt.) at the rate of 60 ml/hr; the molar ratio of MN was 8.06. When polymerization began the inflow of the propylene and of the ethylene was adjusted to compensate for the greater reactivity of the latter. The average ratio of propylenelethylene by weight was 2.3 (as determined by periodic gas chromatographic analyses). After 1.25 hours polymerization was stopped by displacing the gas mixture with nitrogen and stopping the catalyst addition. The reaction mixture was then washed twice with methanol to deactivate and remove the catalyst. The yield based on the amount of vanadium catalyst used was 1,680 grams of polymer per gram of VOCl The recovered copolymer had a number average molecular weight (MW) of 28,000 (determined by vapor pressure osmometry); 159 pendant methyl groups per 1000 chain carbon atoms (determined by infrared spectroscopy), and an inherent viscosity of 2.28 dl/g. (measured in decalin at 135C. and 0.lg./l00 ml). PART B. OXIDATION OF THE COPOLYMER A solution of 70 grams of the copolymer, obtained in Part A, above, in 1,000 grams of heptane was heated to 250F. while blowing with nitrogen to remove the heptane. 280 grams of a SAE 5W mineral oil was gradually added as the heptane was removed, and the viscous oil-copolymer mixture brought to 430F. with vigorous stirring. Blowing with nitrogen was discontinued at this point, to allow atmospheric oxygen to diffuse into the reaction vessel. After 0.5 hour, thermal and oxidative degradations reduced the viscosity of the mixture such that vigorous stirring could be maintained at the optimum oxidation temperature of 310F. Heating with stirring was continued at such temperature for a total of 2.5 hours. Conversion, as measured by silica gel chromatography, was 100 percent.

PART C. AMINATION OF THE OXIDIZED CO- POLYMER Two hundred grams of the oxidized copolymer, obtained as in Part B, above, l0 percent active oxidized copolymer in SAE 5W mineral oil diluent, i.e., grams net oxidized copolymer) was mixed with 500 ccs. benzene, and the temperature of the solution brought to 120F. under a nitrogen blanket; the nitrogen being introduced at the rate of 1.0 CFH. Molten anhydrous hexamethylene diamine (0.42 grams, 0.0036 mole) was added in one lot to the oxidized copolymer-benzene-oil solution at 140F. The resultant mixture was rapidly brought to the reflux temperature of benzene (l76F.). Maintaining a nitrogen blanket, benzene and water-of-reaction were distilled from the reaction mass, until the distillate was clear, indicating the absence of residual water. The temperature was increased to 320F. and nitrogen introduced at the rate of 6 CFH. to remove residual benzene from the reaction mass. Heating and nitrogen blowing were continued for about an hour to remove the last traces of volatile impurities. The recovered product had an activity of 10 percent (amount of active aminated product in the recovered reaction mass) and a nitrogen content of 0.046 percent.

The dispersancy effectiveness of the additives of the present invention is demonstrated by the so-called Spot Dispersancy Test. In this test, a measured amount of the additive to be tested is mixed with a measured volume of crankcase lubricant oil formulation which has been used in a Lincoln Sequence V engine test for 394 hours (twice the time of the standard test time). This composition is heated and stirred at about 300F. for about 16 hours, and an aliquot is transferred to blotting paper. A control is made at the same time by stirring and heating at 300F. for 16 hours a second oil from the 394 hour Lincoln Sequence V engine test, and depositing an aliquot on blotting paper. At the same time, a readily available commercial ashless dispersant is mixed in the same manner as above, for comparison purposes. The deposits on the blotting paper are measured to obtain the average diameter of the outer oil ring (Do), and the average diameter of the inner sludge ring (Da). The ratio of Da/Do is an indication of the detergent-dispersant property of the addition agent.

The data in Table I, below, demonstrate the effectiveness of the products of the present invention as dis persants in lubricants. The following samples were employed in this test:

Sample A Control Oil; no dispersant Sample B Control Oil plus 2% of the aminated oxidized copolymer of Example I, Part B.

TABLE I SALAPLE PERCENT DISPERSANCY SAMPLE A Solvent-extracted SAE 5 Oil 37.15% (Vol.) Solvent-extracted SAE l0 Oil 47.00% do. Polybutene VI lmprover 2.80% do. Polymethacrylate VI Improver 4.95% do. Zinc dialkyl dithiophosphate l.l0% do. High-base Magnesium Sulfate 2.00% do. Aminated Oxidized Copolymer, Example I 5.00% do.

Part B The data obtained in the test are given in the following Table II.

TABLE II ENGINE RATINGS SAMPLE SLUDGE VARNISH "In this test a rating of 50 is perfect.

Sample A I50 Neutral Base Oil Sample B Sample A plus l% of the aminated oxidized copolymer of Example ll, Part C, supra.

TABLE Ill SAMPLE SSU VISCOSITY AT 2l0F. V.l.

The above data demonstrate that the high molecular weight aminated oxidized copolymers of the present invention are effective in imparting the desired V.l. property to a low V.l. base oil stock.

Percentages given herein and in the appended claims are weight percentages unless otherwise stated.

Although the present invention has been described with reference to certain specific preferred embodiments thereof, the invention is not limited thereto, but includes within its scope such modifications and variations as come within the scope and spirit of the appended claims.

We claim:

I. The oil-soluble product prepared by the process comprising, reacting at a temperature of from about 140 to about 350F. an oxidized high molecular weight amorphous copolymer of essentially ethylene and propylene, said copolymer having a number average molecular weight of at least about 1,500, and at least 150 pendant methyl groups per l,000 chain carbon atoms, with a primary or secondary aliphatic amine selected from the group consisting of an alkyl amine having from about 2 to about 12 carbon atoms, an aliphatic diamine of the general formula H N(CH ),,NH wherein y is an integer of from about 3 to about 10, and a polyalkylene polyamine of the general formula wherein A is a divalent alkylene radical of from about 2 to about 6 carbon atoms, and x is an integer of from 1 to about 10, said reactants being used in the molar ratio of from about 1:2 to about 1:20, respectively.

2. The oil-soluble product of claim 1, wherein said copolymer comprises essentially ethylene and from about 30 to about 65 mole percent propylene.

3. The oil-soluble product of claim 1, wherein said copolymer comprises essentially ethylene, from about 30 to about 65 mole percent propylene, and up to about 10 mole percent of a third olefinic monomer selected from the group having the general formula RCH=CH wherein R is an aliphatic or cycloaliphatic radical of from 2 to about 20 carbon atoms, and diolefinic monomers having from about 4 to about 25 carbon atoms.

4. The oil-soluble product of claim 3, in which the third olefinic monomer is l-decene.

5. The oil-soluble product of claim 1, in which the aliphatic diamine is hexamethylene diamine.

6. The oil-soluble product of claim 1, in which the polyalkylene polyamine is tetraethylene pentamine.

7. A lubricant composition comprising a major proportion of a normally liquid oleaginous lubricant, and from about 0.1 to about 10 percent of the oil-soluble condensation product defined in claim 1.

8. A lubricant composition comprising a major proportion of a normally liquid oleaginous lubricant, and from about 0.1 to about 10 percent of the oil-soluble condensation product defined in claim 2.

9. A lubricant composition comprising, a major proportion of a normally liquid oleaginous lubricant, and from about 0.1 to about 10 percent of the oil-soluble condensation product defined in claim 3.

10. A lubricant composition comprising, a major proportion of a normally liquid oleaginous lubricant, and from about 0.1 to about 10 percent of the oil-soluble condensation defined in claim 4.

11. A lubricant composition comprising, a major proportion of a normally liquid oleaginous lubricant, and from about 0.1 to about 10 percent of the oil-soluble condensation product defined in claim 6.

12. An addition agent concentrate for lubricating oils, comprising a lubricating oil containing from about 10 to about percent of the oil-soluble product defined in claim 1.

' UNITED sll'lz-is PATENT OFFICE 5 69 (I! QERTIFICATE OF. CORRECTION Patent No r 3,86%2 Dated February b 975 lnventofls) George s. Culbertson and Robert E. Karll It is certified that error appears in the above-identified patent Q and that said Letters Patent are hereby corrected as shown below:

Col Line 36 "additive" should be addition l2 "olefine" should be olefin l8 "olefine" should be olefin 4 22 "l,7octadiene" should be 1,7-octadiene, l6 Delete dash at end of line +1 "polymer as" should be polymer obtained as o Signed and gealcd this second D3) Of September 1975 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (mnmissimu'r oflatenls and Trademarks o I x 

2. The oil-soluble product of claim 1, wherein said copolymer comprises essentially ethylene anD from about 30 to about 65 mole percent propylene.
 3. The oil-soluble product of claim 1, wherein said copolymer comprises essentially ethylene, from about 30 to about 65 mole percent propylene, and up to about 10 mole percent of a third olefinic monomer selected from the group having the general formula RCH CH2 wherein R is an aliphatic or cycloaliphatic radical of from 2 to about 20 carbon atoms, and diolefinic monomers having from about 4 to about 25 carbon atoms.
 4. The oil-soluble product of claim 3, in which the third olefinic monomer is 1-decene.
 5. The oil-soluble product of claim 1, in which the aliphatic diamine is hexamethylene diamine.
 6. The oil-soluble product of claim 1, in which the polyalkylene polyamine is tetraethylene pentamine.
 7. A lubricant composition comprising a major proportion of a normally liquid oleaginous lubricant, and from about 0.1 to about 10 percent of the oil-soluble condensation product defined in claim
 1. 8. A lubricant composition comprising a major proportion of a normally liquid oleaginous lubricant, and from about 0.1 to about 10 percent of the oil-soluble condensation product defined in claim
 2. 9. A lubricant composition comprising, a major proportion of a normally liquid oleaginous lubricant, and from about 0.1 to about 10 percent of the oil-soluble condensation product defined in claim
 3. 10. A lubricant composition comprising, a major proportion of a normally liquid oleaginous lubricant, and from about 0.1 to about 10 percent of the oil-soluble condensation defined in claim
 4. 11. A lubricant composition comprising, a major proportion of a normally liquid oleaginous lubricant, and from about 0.1 to about 10 percent of the oil-soluble condensation product defined in claim
 6. 12. An addition agent concentrate for lubricating oils, comprising a lubricating oil containing from about 10 to about 75 percent of the oil-soluble product defined in claim
 1. 